Clothing Thermal Insulation Research Articles

Measurement of clothing thermal insulation and moisturevapour resistance using a novel perspiring fabric thermalmanikin

Thermal manikins are necessary instruments for measuring thethermal insulation and moisture vapour resistance of clothingsystems, which are important parameters relevant to clothingthermal comfort. Although many thermal manikins have beendeveloped since the first example in the 1940s, simulation ofhuman perspiration in thermal manikins remains a challenge. This paper reports on a novel perspiring fabricthermal manikin, which simulates gaseous perspiration bymoisture transfer through a `skin' made of a breathable fabric.The manikin has been used to measure the thermal insulation andmoisture vapour resistances of clothing ensembles, anddemonstrated high accuracy and reproducibility.

Analysis of Air Gap Size and Distribution in Single and Multilayer Clothing Systems Using 3-D Whole Body Digitizing

Today's three-dimensional (3-D) whole body digitizers provide accurate representations of the surface of the human body relatively quickly and easily. These 3-D data provide a novel means for visualizing and quantifying the interface between the user and their clothing or equipment. In this paper we discuss how images from a Cyberware 3-D whole body digitizer are used to determine local and global distributions of air gaps in single and multilayer clothing systems. Quantifying air gap sizes and distributions and their effects on clothing thermal insulation is one aspect of a multidisciplinary research effort directed toward improving flame/thermal protective clothing. We begin with our method for collecting and editing the scan data. We then describe how we identify and quantify air gaps in the clothing systems. Examples are given that show concordance between air gap distribution and burn patterns obtained from full-scale manikin fire tests. We finish with a discussion of the role 3-D digitizing will play in the development of burn test simulation software. The simulation software will incorporate scan data, lab-and full-scale burn test results.

The Effect of Lower Opening on Thermal Insulation of Clothing System. Measured by Simulated Skin.

Thermal insulation and ventilation capacity of clothing are one of the most important properties concerning the thermal comfort of the human body. Though both of above properties are needed for winter clothing, it is difficult to get a clothing with both good thermal insulation and good ventilation capacity only by fabric properties like thermal conductivity and air permeability because a clothing with good ventilation capacity has little thermal insulation and vice versa. This paper aimed to find a most compromising condition by changing clothing constructive factors like size of air space and open-closed situation of lower opening of air space of clothing. Ventilation capacity was affected by both air permeability of a clothing material and an open-closed situation of lower opening. It was already made clear in a previous paper _??_1_??_ that the air permeability of clothing material did not affect on heat transfer of clothing when the human model was standstill, the size of air space of clothing was more than 10mm and there was no forced flow in surroundings. So ventilation could be caused only by the penetration through lower opening. By experiments using vertical hot-plate and theoretical calculation, follows were clarified. Open-closed situation of lower opening affected on thermal insulation largest when the size of air space was 10mm. Thermal efficiency of closed case was 1.45 times as large as that of open case. However, from a viewpoint of ventilation, an open situation was desirable. If this situation occurred in a real clothing system, an unevenness of thermal insulation along the height would increase chilliness near “legs”.

Effects of skin surface temperature distribution of thermal manikin on clothing thermal insulation.

Effects of the distribution of skin surface temperature were investigated on thermal insulation of clothing for whole and each body part. The experiments were carried out with a thermal manikin in a climatic chamber. The two types of clothing ensemble were measured. The measurement with nude thermal manikin were also conducted. The three variations of skin temperature distribution were set with the thermal manikin. The values of the thermal insulation of nude skin surface (Ia), the total thermal insulation of clothing (It) and the basic thermal insulation of clothing (Icl) were measured with this thermal manikin under each skin temperature distribution. As a result, the values of Ia and It were not affected by skin temperature distributions of the range of typical experimental conditions. However, It is necessary to carefully use the values of the thermal insulation of clothing for the body parts, because these values were more influenced by the skin temperature distribution than those for the whole body.

Clothing, assessment and effects on thermophysiological responses of man working in humid heat

This paper presents the relative importance of the different factors to be taken into account when predicting thermal exchanges when man is wearing garments while being exposed to warm environments. Factors considered are the thermal insulation of clothing (CLO), the thermal efficiency of clothing (Fcl), the clothing area factor (fcl), the pumping coefficient (p), the vapour permeation efficiency factor (Fpcl). As Fpcl depends on CLO, Fcl,fcl and p factors, physiological assessments of this factor appears to be necessary for the calculation of the maximum evaporative capacity (Emax) in clothed subjects. In this paper, comparisons of body temperatures, whole body and local sweating were made from data obtained on both unclothed and then clothed subjects working at 50 watts on a cycloergometer in warm environments (Ta = Tr = Tsk), with increasing ambient humidity levels (Pa). Results showed that clothed subjects sweated more than unclothed man for the same Pa increases and hidromeiosis occurring on the skin of unclothed man seemed to be responsible for this. Sweat accumulation in the clothes confirms that the decrease in the evaporative sweat efficiency for clothed subjects was closely associated with the threshold for occurrence of core temperature drift. However the less important slope in the Tcore vs delta Pa relationship for clothed subjects compared to that for unclothed implies a more efficient body cooling thanks to clothing, which does not lead to as great a physiological disadvantage as expected. Pumping effect and additional concurrent evaporation could account for this phenomenon: the ISO model (Required sweat rate) which includes an additional air velocity as a function of metabolism allows us to consider this beneficial influence of increased Emax in clothed subjects. However this effect should not be considered when the model is used for unclothed subjects.

AN INVESTIGATION ON THE EFFECTS OF BODY MOTION, CLOTHING DESIGN AND ENVIRONMENTAL CONDITIONS ON THE CLOTHING THERMAL INSULATION BY USING A FABRIC MANIKIN

The effects of body motion, clothing design and environmental conditions on the thermal insulation of clothing systems were investigated by using a newly developed fabric manikin. The manikin was covered with four typical clothing systems, and the changes of thermal insulation of these clothing systems and the heat lost from the clothed manikin were examined under various walking speeds (0–1.2 km/hr), wind velocities (0–2.2 m/s), and ambient temperature (—20°C–20°C) inside an environmental chamber. Out of this work, better understanding of the reduction of thermal insulation, owing to the combined effects of body motion and wind, are achieved. Also, the work showed the significant effect of ambient temperature on the effective clothing thermal insulation and the advantage of using aluminium foil in the construction of clothing for use in cold environments. Finally, the work revealed the fact that body motion can have a very significant effect on the clothing thermal insulation even though body activity is low. This explains why people, when they feel cold, like to increase their activity level in order to increase heat production rather than reduce their activity level to reduce the heat lost.

Factors influencing the body temperature of 3-4 month old infants at home during the day.

Continuous recordings of rectal temperature were made from 40 normal infants, aged 3-4 months, at home during two days of normal activities. We found that the rectal temperature of a normal, healthy baby may vary from 36.0 degrees C at night to 37.8 degrees C during active periods of the day. During daytime sleep rectal temperature fell, but to a lesser extent, and for less time than during night time sleeps. Feeds raised the temperature unless the baby slept, when they reduced the rate of fall of temperature. Bottle feeds affected temperature more quickly than breast feeds. The changes in temperature during sleep and after feeds were independent of the room temperature or thermal insulation of clothing and wrapping.

The thermal environment in which 3-4 month old infants sleep at home.

The thermal insulation of clothing and wrapping (tog value), room temperature, and body temperature was measured for 3-4 month old infants sleeping in their home cots under conditions chosen freely by parents during a cold winter. We found that ambient temperature averaged 18.4 degrees C when infants were put down, but fell by an average of 4.4 degrees C during the night. Minimum room temperature correlated with outside temperature, but most rooms were heated to some degree; smaller babies were kept in warmer rooms. The tog value of clothing before putting the baby down averaged 5.1, supplemented by 9.6 tog units of wrapping in the cot--a 188% increase for a 4.4 degrees C drop in temperature. Total tog of clothing and wrapping correlated negatively with minimum room temperature; smaller born babies tended to be more heavily wrapped. Despite the large increase in insulation in the cot, most babies maintained normal body temperatures.

Thermal Insulation of Fire Fighter's Protective Clothing in Hot Environment

Thermal Insulation of Fire Fighter's Protective Clothing in Hot Environment

A THEORETICAL AND EXPERIMENTAL STUDY OF THE THERMAL INSULATION OF CLOTHING IN WINDY CONDITIONS

A theoretical model for the study of the thermal insulation of clothing in windy conditions is presented. In this model, the trunk of a human body is approximated to as an internally temperature‐controlled hollow cylinder. The clothing assembly covering on the cylindrical body consists of two parts, an outer wind resistant fabric and an inner porous fibrous material. The numerical solution derived agrees well with the experimental findings performed on a cylindrical togmeter in a wind tunnel. It appears that air penetration and changes in clothing geometry caused by compression, expansion or fluctuation of the assembly are two essential mechanisms which cause the wind‐induced reduction in thermal insulation. The effects of wind velocity, air permeability of the outer fabric and inner porous fibrous material, are examined and discussed.

Comparison between required clothing insulation and that actually worn by workers exposed to artificial cold

Required Clothing Insulation (IREQ) is a new thermal index submitted to the International Organisation for Standardisation (ISO) for discussion. It is designed to prevent general body cooling and is based on an analysis of heat exchanges. The thermal clothing insulation actually worn (lcl) is estimated using a new method, also submitted to ISO. IREQ of 54 workers exposed to artificial cold (air temperature between −30° C and +10° C) was compared with lcl actually worn by these workers. The results of the present study show that, on average, the workers choose accurately lcl they need if their IREQ is below and up to 1·5 clo. Moreover, these workers prefer to wear garments which provide them with thermal comfort. If IREQ of workers is higher than 1·5–2 clo (i e, workers exposed to −20° C), it is difficult for them to increase their thermal insulation with additional garments. Although their lcl is not sufficient, there is no risk of gradual body cooling because of their continuous time exposure (CTE) which is shorter than the calculated Duration Limited Exposure (DLE). On the other hand, Wind Chill Index (WCI), which is proposed to prevent local cooling, is better adapted to prevent cold injuries than physiological thermal strain; for example, impairment of manual dexterity cannot be prevented with this index.

Pumping effects on thermal insulation of clothing worn by human subjects.

This study was undertaken in order to analyse the importance of the pumping effect on clothing's thermal insulation. To enhance differences in heat exchanges due to the pumping effect, two sets of condition were fixed, minimizing either the convective or the radiative heat transfers. The results showed that: (i) the clothing insulation determined on a manikin, even if he is moving, is larger than the resultant clothing insulation for living subjects; (ii) the insulation is not the same for radiant heat or cold as for convective heat or cold;(iii) the pumping effect can increase or decrease the resultant clothing insulation; (iv) the clothing insulation is smaller in warmer conditions thanin cooler ones; (v) it becomes necessary to make a definite distinction between several kinds of clothing insulation; intrinsic or basic insulation against radiation and convection; effective insulation against radiation and convection taking into account only the heat flowing through the clothing fabric; resultant insulation taking into account the magnitude of the pumping effect when clothing is worn by living subjects

Experimental Study on the Thermal Insulation of the Typical Clothing among Higher Aged Women in Nagano District

Experimental Study on the Thermal Insulation of the Typical Clothing among Higher Aged Women in Nagano District

A Method for Computing Optimal Heat-Regulating Properties of Clothing on the Basis of the Probability of Variation of Meteorological Factors

AbstractThe heat-insulating requirements of clothing have been determined in the past on the basis of mean monthly meteorological data that do not take into account the probability of climatic factors fluctuating within a month. A computational method is offered to determine optimal values for the thermal insulation of clothing required in various parts of Siberia in various seasons and for different physical work loads—resting-sitting, light work, heavy work—in the light of the probability of day-to-day fluctuations of weather elements.

A Simple Calorimeter for the Simultaneous Determination of Heat Loss and Heat Production in Animals

This paper describes a new type of gradient calorimeter which permits the rapid simultaneous measurement of respiratory metabolism and heat loss. It uses the temperature difference between the inner and outer aspect of a fixed transitional layer of air rather than adiabatic principles. (W. O. Atwater and F. G. Benedict, ``A respiration calorimeter with appliances for the direct determination of oxygen,'' Publication 42, Carnegie Institute of Washington (1905); G. Lusk, Arch. Int. Med. 15, 793 (1915); E. F. DuBois, Basal Metabolism in Health and Disease (Lea and Febiger, Philadelphia, 1936), third edition; Forester, Ferris, and Day, Am. J. Physiol. 146, 600 (1946); L. Love and H. C. Bazett, Fed. Proc. 7, 74 (1948); C. P. Yaglou, ``Thermal insulation of clothing,'' unpublished data; T. Benzinger, personal communication.) Application of gradient principles to calorimetry so simplifies heat loss determinations that they become the easiest and most accurate part of the procedure.